For many automotive enthusiasts, the idea of a Toyota V12 engine is shrouded in myth and legend. While Toyota is renowned for its reliable and innovative engines, the V12 configuration remains a rare gem in their illustrious history. The heart of this automotive enigma lies within the Toyota Century, a limousine that stands as the ultimate expression of Japanese luxury and craftsmanship. This article delves into the fascinating world of the Toyota Century V12, exploring its history, engineering marvel, and why this engine, the 1GZ-FE, is so highly coveted.
Toyota Century: More Than Just a Lexus
Before diving into the intricacies of the V12, it’s crucial to understand the Toyota Century’s position in the automotive landscape. Contrary to common assumptions, Lexus is not Toyota’s flagship model. That prestigious title belongs to the Century limousine, a vehicle steeped in tradition and exclusivity.
Introduced in 1967, the Century was conceived as a premium limousine catering to Japan’s elite – high-ranking government officials, business executives, and even the Japanese Imperial Household. The name “Century” commemorates the 100th anniversary of the birth of Sakichi Toyoda, the founder of Toyota Industries.
Classic Toyota Century
Initially based on the Toyota Crown V8, the first generation Century maintained its classic, dignified appearance with minimal external changes until 1997. Beneath the surface, however, it received continuous upgrades to its drivetrain and interior appointments, reflecting its status as a vehicle of utmost refinement.
In 1997, Toyota unveiled a completely redesigned Century, the GZG-50 series. While the exterior retained the subtle elegance and classic lines of its predecessor, a revolutionary change lay under the hood. This new Century debuted Toyota’s, and indeed Japan’s, first and only production V12 engine – the 1GZ-FE.
Priced around $US 95,000 in Japan, the Century represents exceptional value, especially considering the meticulous attention to detail in its construction. Even the exterior sheet metal undergoes a polishing process before painting, a testament to Toyota’s unwavering commitment to quality.
Alt text: The impressive engine bay of a Toyota Century, housing the rare 1GZ-FE V12 engine, highlighting its sophisticated engineering and commanding presence.
Given its limited production, primarily for the Japanese domestic market with a modest monthly sales target of just 200 units, Toyota’s decision to develop a V12 engine for the Century is remarkable. It speaks volumes about their dedication to pushing engineering boundaries, even if it meant potentially selling the vehicle at a loss. The sheer volume of Corollas produced daily likely subsidizes such ambitious projects, allowing Toyota to showcase its engineering prowess.
For many enthusiasts outside Japan, the Toyota Century V12 is less about the complete car and more about the engine itself. The 1GZ-FE has become a sought-after powerplant for engine swaps and custom car builds, overshadowing the sophisticated limousine it originally came in.
1GZ-FE: Decoding Toyota’s V12 Masterpiece
So, what exactly is a 1GZ-FE? In essence, it’s a 5.0-liter, all-aluminum, 48-valve quad-cam V12 engine. However, in true Toyota fashion, “simple” is not a word that accurately describes its engineering complexity and sophistication. Toyota spared no expense in equipping this engine with top-of-the-line features:
Alt text: A detailed schematic diagram of the Toyota 1GZ-FE V12 engine, illustrating its intricate components, including the quad-cam configuration and 48 valves.
- Robust Bottom End: Features 6-bolt main bearings and a forged steel crankshaft for exceptional durability and high-RPM stability.
- Lightweight Construction: Utilizes an aluminum alloy block and heads, reducing weight and improving thermal efficiency.
- Advanced Valve Timing: Continuously Variable Valve Timing-intelligent (VVT-i) optimizes valve timing for enhanced performance and fuel efficiency.
- Optimized Intake System: Variable Length Inlet Runners (ACIS) adjust intake runner length to maximize torque across the RPM range.
- Precise Ignition: Direct fire ignition with waste spark ensures reliable and efficient combustion.
- Efficient Fuel Delivery: Sequential fuel injection provides precise fuel metering for each cylinder.
- Electronic Throttle Control: Electronic throttle control (‘fly by wire’) offers precise throttle response and integration with vehicle systems.
The 1GZ-FE is a proud member of Toyota’s BEAMS (Breakthrough Engine with Advanced Mechanism System) engine family, sharing this distinction with engines like the renowned 3S-GE found in the Altezza. Interestingly, the 1GZ-FE can be viewed as two inline six-cylinder engines sharing a common crankshaft.
This “twin-engine” concept is evident in its design. It features dedicated left and right cylinder bank intake manifolds, throttle bodies, and EFI systems. Remarkably, it even employs separate ECUs for each bank, allowing the engine to function as a six-cylinder in the event of a major failure in one bank – a testament to its redundancy and reliability.
1GZ-FE Engine Specifications
| Feature | Specification |
|---|---|
| Total Displacement (cc) | 4,996 |
| Cylinder Configuration | 60-degree V12 |
| Bore x Stroke (mm) | 81.0 x 80.8 |
| Combustion Chamber | Pent roof type |
| Compression Ratio | 10.5:1 (97 Octane Recommended) |
| Fuel Supply System | Electronic Fuel Injection (EFI) |
| Fuel Tank Capacity (Century) | 95 Liters |
| Valves | DOHC 4-valve, Chain & Gear Drive |
| Maximum Output (PS @ rpm) | 280 @ 5,200 net |
| Maximum Torque (kg-m @ rpm) | 49.0 @ 4,000 net |
| Alternator Output | 1440 Watts |
| Starter Motor Power | 2 kW |
| Firing Order | 1-4-9-8-5-2-11-10-3-6-7-12 |
| Spark Plug Type & Gap | Denso Iridium SK16R11, 1.0-1.1mm |
| Intake Valve Opening | -7 to 53 degrees BTDC |
| Intake Valve Closing | 57 to -3 degrees ATDC |
| Exhaust Valve Opening | 41 degrees BBDC |
| Exhaust Valve Closing | 3 degrees ATDC |
| Recommended Oil Grade | API SH EC-II, SJ EC or ILSAC |
| Oil Viscosity & Capacity | 5W-30, 8 Liters |
| Oil Filter | Toyota 15601-68010 |
In keeping with Japanese automotive industry norms of the time, the official output was rated at approximately 280 horsepower. Export versions were sometimes rated slightly higher at 220 kW (roughly 300 horsepower) with a torque figure of 460 Nm (around 350 ft-lbs).
However, the true strength of the 1GZ-FE lies in its torque delivery. It generates over 400 Nm of torque from as low as 1000 rpm, providing the hefty 2000kg Century limousine with surprisingly brisk acceleration and effortless cruising.
Alt text: A comparative graph illustrating the horsepower and torque curves of the 1UZ-FE V8 engine versus the Toyota Century 1GZ-FE V12, clearly showing the V12’s superior torque across the entire RPM range.
Comparing it to Toyota’s renowned 1UZ-FE V8 engine reveals the V12’s significant torque advantage. In fact, the 1GZ-FE V12 produces comparable power and even more torque across the entire rev range than the legendary Ferrari BB 512 of the 1980s. This abundance of low-end torque makes it exceptionally well-suited for applications requiring smooth, effortless power.
Unparalleled Smoothness and Refinement
As befitting a flagship engine, Toyota prioritized smoothness above all else in the 1GZ-FE’s design. A V12 configuration inherently offers superior smoothness due to the more frequent power strokes compared to engines with fewer cylinders. For any given RPM, a V12 has power strokes occurring three times as often as a four-cylinder engine.
Several design features further enhance the engine’s smooth operation:
- Slant-Squish Combustion Chambers: Promote stable and efficient combustion.
- Iridium Spark Plugs: Ensure consistent and reliable ignition.
- Variable Valve Timing-intelligent (VVT-i): Fine-tunes valve timing to optimize combustion and reduce vibrations.
Toyota described the Century V12’s operation as being “like that found in electric motors,” emphasizing its exceptional smoothness and quietness. The VVT-i system, acting on the intake camshafts, can advance valve timing by up to 60 degrees, further contributing to smooth power delivery and efficiency.
The cylinder heads feature a valve angle of 24.3 degrees, with 30mm diameter intake valves and 24.5mm exhaust valves, both utilizing 5.5mm diameter stems. Titanium-coated valve adjusting shims, positioned above aluminum alloy valve lifter buckets, minimize friction and wear.
Continuously adjusting valve timing based on driving conditions optimizes torque, power, and fuel efficiency while reducing emissions of NOx and HC. While the V12 is not inherently fuel-efficient, it is relatively economical considering its power output and torque. Real-world fuel economy for the 2-tonne Century is quoted at around 7.2 km/l.
Complementing the VVT-i system is a variable length intake system that switches between two intake runner lengths. This optimizes torque in the low to mid-range, which is most beneficial for everyday driving. Experts at Link Electrosystems, aftermarket ECU manufacturers, consider the variable intake runner length to have a more significant impact on torque delivery than even variable valve timing.
Combined with a rigid engine block and balanced reciprocating components, the V12 exhibits 10% less vibration than the already exceptionally smooth 1UZ-FE Lexus V8. Titanium-coated valve shims and low-viscosity 5W-30 engine oil further minimize friction.
Construction and Components
The 1GZ-FE’s bore and stroke dimensions are similar to Toyota’s 1JZ-GE inline-six engines. The all-aluminum 60-degree cylinder block employs thin-wall cast iron liners pressed into place, with cylinder bores on a 93mm pitch. This design makes the V12 slightly narrower than the 90-degree 1UZ-FE V8, although it is approximately 120mm longer. Pistons are made of aluminum alloy and feature a taper squish design with semi-floating piston pins.
Similar to the 1UZ-FE, the V12 uses sintered and forged connecting rods, which are asymmetrical and specific to the left or right cylinder bank.
The forged crankshaft runs in seven aluminum alloy bearings and incorporates 12 balance weights for smooth operation.
Ignition System
The 1GZ-FE employs a direct ignition system (DIS) with a waste spark configuration. The front six cylinders have individual coils mounted directly on the spark plugs. However, each coil also has a pigtail plug lead that connects to another spark plug, firing in pairs.
The firing order is 1-4-9-8-5-2-11-10-3-6-7-12, with the following spark plug pairings:
- 1 & 11
- 3 & 9
- 5 & 7
- 2 & 12
- 4 & 10
- 6 & 8
The spark plugs are iridium-tipped Denso SK16R11 with a 1.0 to 1.1 mm electrode gap.
Crankshaft and Camshaft Position Sensors
Reflecting its “twin-engine” nature, the V12 is equipped with two crankshaft angle sensors positioned 180 degrees apart, reading from a common timing rotor. The rotor has a ’36 minus 2′ configuration, with teeth spaced 10 degrees apart and two adjacent teeth missing, resulting in 34 teeth in total.
A camshaft position sensor is located at the rear of each intake camshaft, featuring three evenly spaced teeth on the timing rotors.
VVT-i (Variable Valve Timing-intelligent)
The VVT-i system on the 1GZ-FE provides up to 60 degrees of intake camshaft advance, measured in crankshaft angle. This system enhances torque, improves fuel economy, and reduces emissions.
Fuel Injection
The engine utilizes 12-cylinder sequential fuel injection. For aftermarket ECU installations that may have limitations on sequential injector drives, injectors can be rewired in pairs. The fuel system operates with a standard supply and return setup, maintaining a normal fuel pressure of around 41 PSI, dropping to 31 PSI at idle.
Electronic Throttle Control (ETCS-i)
The 1GZ-FE features Toyota’s Electronic Throttle Control System-Intelligent (ETCS-i), also known as ‘fly by wire.’ The accelerator pedal has a position sensor that sends a signal to the engine ECU. This ECU then controls two throttle motors (one for each throttle body) to open the throttle butterflies. A standard throttle position sensor provides feedback to the ECU.
Alt text: Close-up view of the dual throttle bodies of the Toyota Century V12 1GZ-FE engine, showcasing the electronic throttle control mechanism (ETCS-i).
The throttle motor also manages idle speed control, cruise control, traction control, and ABS functions.
Air Flow Meters
The 1GZ-FE employs two independent hot-wire air flow meters to measure intake air volume for each cylinder bank.
Sump Design
As the 1GZ-FE is exclusive to the Toyota Century, it has a unique sump design with the bowl located at the front. The sump consists of an alloy upper pan and a pressed steel lower bowl, holding approximately 8 liters of 5W-30 oil. The oil filter is notably large, shared with diesel Land Cruiser models.
Timing Chains
The 1GZ-FE uses three timing chains instead of a timing belt, offering increased durability and longevity, potentially lasting the engine’s lifespan. Chain tension is maintained by both spring-loaded and oil pressure-controlled tensioners.
Alt text: Front view of the Toyota Century 1GZ-FE V12 engine, clearly showing the robust timing chain setup, a hallmark of Toyota’s engine reliability.
Ancillary Components
The 1GZ-FE shares similarities with the 1UZ-FE V8 in terms of ancillary components:
- Air Conditioning Compressor: Similar design and mounting location to the 1UZ.
- Power Steering Pump: Similar to the 1UZ unit with an integral reservoir, although some fittings may differ.
- Alternator: Similar to the 1UZ, rated at 1440 watts.
- Starter Motor: Mounts on the left side under the exhaust manifold, drawing upwards of 2 kW. Due to the 60-degree V-angle, it cannot be positioned between the heads like in the V8.
Transmission and Gearing
The Toyota Century received a minor upgrade in 2001, believed to coincide with the transition from a 4-speed to a 6-speed automatic transmission. The earlier 4-speed automatic was a variant of the A342E, also found in the JZA70 Supra with the 2.5-liter twin-turbo 1JZ-GTE engine (1990-1993).
Gear ratios for the 4-speed automatic are:
- Low: 2.531
- Second: 1.531
- Drive: 1.0
- Overdrive: 0.753
- Reverse: 1.880
- Differential Ratio: 3.615 (Code A01A, 8” crown wheel diameter)
Standard tire size is 225/60R16, similar in overall diameter to a 245/45×18 tire.
Manual Conversion Potential
The robust nature and enthusiast appeal of the 1GZ-FE have led to interest in manual transmission conversions, particularly for engine swap projects. While originally paired with automatic transmissions, the engine’s architecture and crankshaft design show similarities to the 1UZ-FE V8. This suggests compatibility with aftermarket flywheels and potentially modified 3SGTE units for manual conversions.
Adapting a heavy-duty Supra Turbo 5-speed R154 gearbox is a viable option, offering robustness to handle the V12’s torque. Gearbox adapter plates designed for 1UZ swaps may also be compatible with minor modifications.
Alt text: A Toyota Century V12 bellhousing, a crucial component for manual transmission conversions, showcasing its design for connecting the 1GZ-FE engine to a gearbox.
Photo Courtesy of: Justen Simpson
Manual conversions may require input shaft shortening and hydraulic release bearing systems for clutch actuation. However, the potential for a manual V12 Toyota Century or a custom build powered by a manual 1GZ-FE is a compelling prospect for driving enthusiasts.
Aftermarket ECU Considerations
While ideally, running the 1GZ-FE on its factory engine management system would be preferable, sourcing complete and compatible ECUs, AFMs, and anti-theft systems can be challenging and expensive. Furthermore, the Century’s multiplex communication system between ECUs may pose compatibility issues when used outside of the original vehicle.
Therefore, aftermarket ECUs offer a practical alternative. Link Electrosystems’ Link Plus G3 ECU, for example, is capable of managing the 1GZ-FE. Key considerations for aftermarket ECU implementation include:
- Mechanical Throttle Conversion: Converting from electronic throttle to mechanical throttle operation, potentially by modifying the throttle bodies and utilizing a mechanical throttle mechanism.
- Knock Sensor Management: Managing knock sensing, as aftermarket ECUs may have limitations on the number of knock sensors they can handle.
- Idle Speed Control: Implementing an alternative idle speed control mechanism, potentially using a stepper motor or rotary solenoid valve to bypass air around the throttle bodies.
- Injector Wiring: Wiring injectors in pairs if the aftermarket ECU has limitations on sequential injector outputs.
- Load Measurement: Replacing the factory air flow meters with a manifold absolute pressure (MAP) sensor for load measurement.
Conclusion: The Enduring Allure of the Toyota Century V12
The Toyota 1GZ-FE V12 engine represents a pinnacle of Japanese automotive engineering – a rare and meticulously crafted powerplant designed for ultimate smoothness, refinement, and effortless power. While production numbers remain low due to its exclusive application in the Toyota Century limousine, the 1GZ-FE’s allure continues to grow among enthusiasts.
Its robust construction, advanced features, and inherent V12 smoothness make it a highly desirable engine for custom car builds and engine swap projects. As more 1GZ-FE engines become available outside of Japan, their presence in unique and exciting projects is sure to increase. The Toyota Century V12 is more than just an engine; it’s a symbol of Toyota’s unwavering commitment to engineering excellence and a testament to the enduring appeal of a truly exceptional powerplant.
